Fluorescence and transillumination are used in a variety of applications. In the field of fluorescent microscopes, a white light source is used that is passed through an excitation filter, hits the samples, passes through an emission filter and is imaged by either a human eye or camera to view the patterns of labeled biomolecules or natural fluorescence. In the forensic detection field, forensic scientists have used portable fluorescent detection devices since at least the mid 1980's to visualize either natural fluorescence (blood, semen, bacteria, cocaine) or stained fluorescence (DFO for visualization of fingerprints) that rely on a white light source fitted with a blue excitation filter used in combination with an orange filter attached to either a camera or an observers glasses. In the field of underwater fluorescence photography, divers and scientists have been using UV excitation for visualizing and photographing underwater fluorescent organisms and chemicals since the 1950s, but have more recently turned to white light sources with attached blue excitation filter and integrated emission filters on dive masks and camera lenses. In the medical imaging field, exemplary known applications of transillumination include endoscopy devices, dentistry decay detecting devices, and others, all of which generally use a filtered blue light to detect either the autofluorescence of tissue or bacteria or the stained fluorescence of tissue or bacteria so that the image may be viewed using either colored glasses (for diagnosis or surgery) or a camera with a filtered lens (for documentation). Exemplary endoscopy devices include those disclosed in U.S. Pat. Nos. 4,786,813; 5,507,287; and 5,647,368.
Gel electrophoresis is a group of techniques used by scientists to separate molecules based on physical characteristics such as size, shape, or isoelectric point. This process is widely used and has many applications. For example, it is used to analyze DNA molecules according to their resultant size after being digested by restriction enzymes. It is also used to analyze the products of a polymerase chain reaction (PCR). Typically, it is desirable to visualize and to document the results of the electrophoretic separation test. In this regard, with respect to gel electrophoresis, the use of transillumination and fluorescence in general is widespread. Currently scientists run gels in a separate running base, and then remove the gel for visualization. Often, scientists have to place a unique filter over the gel to visualize the separation of the mixture's components on the gel. Stains are typically used that absorb in the UV range and fluoresce in the visible region (e.g., ethidium bromide). If the analyte molecules fluoresce under ultraviolet light, typically visible background light in the viewing area must be reduced or eliminated to visualize or photograph the stained molecules. In addition, an operator or viewer must protect the skin and eyes from exposure to ultraviolet light, further adding to the inconvenience of imaging the separated molecules.
Another known gel viewer is the SAFE IMAGER™ transilluminator sold by Invitrogen (Carlsbad, Calif.) that uses a visible light source and a first filter between the light source and the stained molecules to block background visible light that is not absorbed by a dye molecule and a second filter between the stained molecules and the viewer to block excitation visible light that is not emitted by the dye used to image the separated molecules. Using a visible light source in combination with filters allows a viewer to visualize stained molecules without the need for protective glasses or clothing.
Invitrogen also provides enclosed mini-gel cassettes called “E-gel®” electrophoresis gels. E-gel® cassettes that contain electrophoresis gels are disclosed in U.S. Pat. Nos. 5,582,702, 5,865,974, and 6,379,516. These cassettes can be inserted into an “E-base™” power supply/cassette holder for running gel electrophoresis. E-gel® cassettes include an ion source for electrophoresis and electrodes within the cassette. Upon insertion of the E-gel® cassette into the E-base™ power supply, electrical contact points connect through the E-base™ power supply to an adapter that can be connected to a power source, such as through an electrical outlet. The E-base™ power supply provides controls and readout displays, as described in U.S. patent application Ser. No. 10/946,472, (U.S. patent application publication 2005/121325) filed Sep. 20, 2004, herein incorporated by reference in its entirety.